CONTINUOSLY VARIABLE TRANMISSION

 Continuously Variable Transmission

Parts of CVT

1.     driving pulley (Vshaped)

2.     driven pulley(Vshaped)

3.     belt(metal /rubber or combination of both)

4.     Sensor

5.     microprocessor.

Continuous variable transmission contains a special type of pulley. Both the driving and driven pulley are conical shape(20°) at one side with a hole in it. A V- shape belt is placed between the two belts as shown in the pic. The belt is made of rubber (modern belt are made of a combination of metal and rubber)

The driving pulley is connecting to the engine while the driven pulley connects to the drive shaft. When the conical pulley are close together they move the belt upwards as shown in pic 1. This also results in an increase in the diameter of the belt meanwhile on other pulley belt groove move downward which decreases the diameter.

 

The distance between the two cones is controlled in many ways like hydraulic pressure, centrifugal force, circuit etc. Whenever the diameter of driven pulley increases the diameter of the driven pulley decrease and vice versa.

As the diameter change is relative to each other we can get infinite no. of gear ratios in this mechanism 

Red pulley is driving and blue is driven pulley (diameter decrease so the velocity increase in driven pulley)

Red pulley is driving and blue is driven pulley (diameter increase so the velocity decrease in driven pulley)

Advantages

1. It works better in changing conditions example in case of throttle and speed changes which eliminates gear hunting

2.In CVT acceleration remains constant at start to high speed .the best thing there is no shift shock hence it provides a smoother ride

3. Better fuel economy

Disadvantages

1. Low torque handling capability due to belt (Maximum torque handling capability 350Nm)

2. CVT is good for light-duty vehicle .In heavy-duty vehicle they have low life

 

 

Cars that used cvt transmission

1.     audi Multitronic

2.     Nissan Murano